A small addition to the original XMLReader of Troybrant which can be found at: 
troybrant.net/blog/2010/09/simple-xml-to-nsdictionary-converter/

With XMLRequestReader, you can send the POST request to your server with parameters as a string.
For example:

NSError *error;
NSDictionary *xmlDict = [XMLRequestReader dictionaryForRequest: @"GetOrderById"
							requestURL: @"http://www.google.com/services/"
							parametersString: [NSString stringWithFormat:@"OrderId=%d&Output=XML", 999]
							error: &error];
NSLog(@"xmlDict: %@", xmlDict);

This method will send a POST request to the web service url: http://www.google.com/services/GetOrderById (I assume that the server will response correctly, you have to put your own URL here!)							
The POST data will be OrderId=999&Output=XML, it's the same as sending a GET request with this URL: http://www.google.com/services/GetOrderById/?OrderId=999&Output=XML (if the server enable the GET request)
The length is determined automatically based on the POST data.
The "Content-Type" is "application/x-www-form-urlencoded"